1. Field of the Invention
The present invention relates to a combined hot water supply system in which plural water heaters are connected in parallel and operated in association with one another.
2. Description of Related Art
Conventionally, there is known a combined hot water supply system in which plural water heaters are connected to a connecting unit to be capable of communicating with each other and the plural water heaters are operated in association with one another by the connecting unit (see, for example, Japanese Patent Application Laid-Open No. 2002-357361).
In such a combined hot water supply system, since relatively small plural water heaters are connected in parallel and can be operated in association with each other, it is possible to reduce overall manufacturing cost and reduce a minimum hot water supply quantity to increase a variable range of a hot water supply quantity. An on-off valve for switching supply of water from a water supply pipe to a heat exchanger and shut-off of the supply of the water is provided in each of the water heaters. The water heater opens the on-off valve according to an instruction from the connecting unit to start operation.
However, a certain degree of a time delay occurs until a burner is ignited and hot water of a target temperature is actually supplied after the on-off valve is opened and water supply to the water heater is started. During this time delay, hot water of a temperature lower than the target temperature is supplied from the water heater to a hot water supply pipe. Therefore, the hot water of the temperature lower than the target temperature is mixed in hot water of the target temperature already supplied from another water heater already operating. There is an inconvenience in that the temperature of hot water supplied from the hot water supply pipe to a faucet substantially falls and unpleasantness is given to a user.
Therefore, it is an object of the present invention to solve the inconvenience and provide a combined hot water supply system in which, when the number of water heaters in operation is increased, the temperature of hot water supplied to a hot water supply pipe is prevented from substantially falling.